We present the results from a non-diffracting optical beam experiment that utilizes extremely low power levels (single-photon). The non-diffracting beam has a Bessel spatial distribution and demonstrates interesting single-photon self-interference effects such as spatial confinement. The single-photon Bessel beam is generated using two means: (1) an attenuated HeNe laser beam that statistically provides a single photon flux through the optical system, and (2) one photon from a pair of quantum entangled twin photons produced by spontaneous parametric down-conversion (SPDC) in a Beta Barium Borate (BBO) crystal pumped by a UV laser. The entangled nature of the single-photon Bessel beam using the SPDC source provides a high level of discrimination from ambient background noise photons that would otherwise severely limit the utility of such a technique to dark enclosures. The HeNe laser on the other hand, provides higher photon count rates and is more convenient to work with in contrast to the entangled photon source. We verify that a single-photon Bessel beam reforms itself beyond a circular obscuration by measuring the transmitted spatial distribution.
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